The invention relates to joint prostheses. More particularly, the invention is directed to cemented stems for engagement with long bones adjacent a prosthetic joint, bone cement and related devices.
Joint replacement surgery is a quite common remedy for osteoarthritis and rheumatoid arthritis. It enables many individuals to function normally when otherwise it would not be possible to do so. Artificial joints are usually comprised of metallic, ceramic and or plastic components that are fixed to existing bone. Such joint prostheses include components for artificial replacement joints for the anatomical joints of elbows, hips, knees, and shoulders. An important consideration in the design and manufacture of virtually any implantable bone prostheses is that the bone prostheses has adequate fixation when implanted within the body.
Early designs of implantable prosthetic joints have relied upon the use of cements such as polymethylmethacrylate (PMMA) to anchor the implant. The use of such cements can have some advantages, such as providing a fixation that does not develop free play or does not lead to erosion of adjoining faces post-operatively. Maintaining a load or force at the bone/cement interface assists in providing for good fixation and to prevent motion. Later designs of implantable articles include implant surfaces that have contours which permit bony in-growth within the implant and which are press-fitted into the bone cavity. The use of the press-fitted stems has been found to be more suitable where the condition of the bone is healthier. For those patients in which osteoarthritis and rheumatoid arthritis have progressed to the point that the bones are highly diseased, the use of a cemented prosthesis is often advised.
When implanting an orthopedic joint implant into a long bone, the orthopedic implant component includes a stem which is fitted into the long bone. The long bone is typically resected and tools in the form of, for example a combination of drills, reamers, and broaches are utilized to prepare the cavity in the long bone. The cavity in the long bone is made larger than the stem of the implant and a layer of cement is positioned between the stem and the cavity of the long bone. Such long bones include the femur, the tibia, the humerus and the ulna for example.
The preparation and procedure for total joint implants, particularly for inserting and positioning stems within a long bone, require additional tools in addition to the drills, reamers, and broaches required for preparing the bone cavity. These tools are necessary to assure a clean, uncontaminated cavity for the filling of the cavity with the bone cement and the prosthetic stem. Such additional tools may include a stem centralizer to centralize the distal portion of the prosthetic stem and cement restrictors which are positioned distally in the stem for isolating the cement to a position proximal of the distal portion of the stem and for preventing the migration of other human tissues distally of the cement restrictor.
Additional equipment desired in a cement prosthetic stem arthroplasty procedure include a femoral pressurizor to assist in pressurizing in this cement. Pressurizing of this cement is advisable to assure that a complete uniform mantle of cement surrounds the stem to support and secure the stem to the bone cavity.
Further to remove the debris created in the tip of the bone cavity during the drilling, reaming, and/or broaching, additional tools are desirable to remove these bone fragments. Such tools include curettes used to remove excess bone cement from the bone cavity. Femoral sponges are also utilized to remove blood and bone debris from the bone cavity. In addition, femoral brushes may be utilized to clean the bone fragments and other debris from the bone cavity.
While cemented stems are generally secured by PMMA, significant differences in PMMA are available. Some PMMA bone cements have very slow curing time while others have quicker curing times. Further, the PMMA cement may include additional compounds to either reduce infection or reduce the pain or such compounds may be anticipated in the future. Further cements may be designed to be more compatible with a particular stem design. It may thus be desirable therefore, to implant a particular prosthetic stem with a particular PMMA cement design for that stem.
Total joint arthroplasty is typically performed in an operating room in a hospital. Typically the operating room is used for any of a wide variety of surgical procedures. Total joint arthroplasty, as with many surgical procedures, requires a large number of instruments as well as the required implants for the surgery. The instruments for the total joint arthroplasty procedures as well as instruments and other equipment necessary for the wide variety procedures for the operating room within the hospital must be maintained in inventory or specifically ordered for the procedure. The need for this vast array of instruments and equipment creates a inventory control and scheduling complexity for the hospital. It is, however, important that the proper instruments and implants are available to the surgeon for a procedure.
While a total joint arthroplasty may be performed if the broach and reamer is available for the preparation of the stem as well as the PMMA cement and the implant, problems can occur when all the necessary cement implant products are not available. For example, if a cement restrictor is not available, it may be difficult for the surgeon to achieve a sufficient pressurization of cement in the femoral canal. The lack of sufficient pressurization in the canal may lead to potential voids within the cement mantle and may result in less than optimal result in the total joint arthroplasty. Similarly, the lack of cement restrictors or centralizers may result in a less than ideal cement mantle for the total joint arthroplasty.
While the availability of all the items necessary for a successful total joint arthroplasty is somewhat difficult to accomplish, the problem is exacerbated for total joint arthroplasty procedures that are not planned. Total joint arthroplasty procedures may be performed as a result of trauma. Such procedures may use what is known as a fracture stem which is implanted in the event of a trauma to the hip. Such fracture stems are often implanted after hours when the trauma occurs. The after hours on call staff may be as not as familiar with the hospital inventories as the regular staff and the after hour staff may have difficulty collecting all the items necessary to perform this surgery.
The present invention is directed to solve at least some of the aforementioned problems.